In cases of extensive gynecologic or pelvic malignancy,
particularly those associated with previous irradiation, the efficacy
of small bowel bypass for obstruction, fistula formation, and stenosis
is well established.

Recently, the efficacy of terminal ileectomy with right
colectomy and Ileotransverse colostomy has also been
demonstrated.

Segmental intestinal resection and anastomosis often
result in numerous incidental enterotomies, with the spillage of intestinal
contents increasing the danger of postoperative pelvic sepsis. The
dissection required for intestinal resection leaves large, raw, irradiated
areas where the new intestinal anastomoses may adhere, necrose, and
produce recurrent fistulae formation. This procedure has been shown
to have an abnormally high operative mortality and, therefore, should
be avoided if possible.

The decision to reexplore the patient 4 to 5
months after the small bowel bypass, take down the bypass segment,
and eliminate the abdominal wall intestinal mucous fistula stoma is
one that requires sound, mature surgical and oncologic judgment. When
in doubt, the mucous fistula stoma should be left in place.

The two most common pathologic events related to pelvic
disease that occur in the small bowel are obstruction and fistula formation
in the terminal ileum. These are demonstrated in Figures 1 and 2. Figure
3 shows the percentages of injuries as related to the intestine, secondary
to pelvic surgery and/or disease. Approximately 85% of all intestinal
problems related to pelvic disease or obstetric and/or gynecologic
surgery are located in the terminal ileum. This is probably because
the terminal ileum generally remains in the true pelvis and, therefore,
is readily accessible to irradiation injury and/or pelvic adhesion
formation.

In contrast, only about 10% of intestinal injuries
are in the rectum or the sigmoid colon, and less than 2% involved either
the transverse colon, jejunum, or other parts of the intestine. This
is an important surgical fact in that it assists the surgeon at exploratory
laparotomy, when multiple dilated loops of bowel are encountered too
rapidly, to identify the diseased segment of small bowel. After identifying
the cecum, the surgeon can trace the terminal ileum back for 3 feet
and find the pathologic problem in 85% of cases. This is far easier
than identifying the ligament of Treitz and tracing the small bowel
distally toward the cecum.

Figures 1 and 2 illustrate the anatomic condition of
the small bowel associated with obstruction and combinations of obstruction
and fistula formation. The small intestine proximal to the obstruction
will be dilated 2-3 times the diameter of intestine distal to the disease.
This is helpful in identification of efferent and afferent loops of
bowel.

The purpose of these operations is to radically resect
or bypass a point of disease in the small bowel.

Physiologic Changes. The terminal
ileum is responsible for absorption of fat-soluble vitamins plus vitamin
B12. Patients who have extensive loss of the ileum can be left with
what has been referred to as short bowel syndrome. This consists of
diarrhea, failure to absorb the fat-soluble vitamins (A, D,E, K) plus
vitamin B12, and difficulty in absorption of high-molecular-weight
fats.

Many of these patients need postoperative assistance
from a medical gastroenterologist to adjust their diet, control diarrhea,
and generally help them to adapt to the rearrangement of their anatomy.

Points of Caution. The most important
aspect of performing a small bowel resection or bypass is to ensure
the vascular integrity of the bowel to be anastomosed. This is aided
by keeping trauma to the bowel wall at a minimum.

All open mesenteric areas must be closed. Internal
hernia and obstruction are serious and can be fatal complications in
these heavily irradiated patients.

The advantage of small bowel bypass over small bowel
resection is that it avoids extensive dissection in a heavily irradiated
fibrotic pelvis. Only that dissection needed to perform the bypass should
be made and, the remainder of the diseased bowel should be left impacted
in the heavily irradiated pelvis. Since both procedures, resection and
bypass, are required at different times in pelvic surgery, however, both
are illustrated in this section.